Transcript Slide 1

SIMULINK-Tutorial 1
Class ECES-304
Presented by : Shubham Bhat
INTRODUCTION
SIMULINK is an extension to MATLAB which uses a icondriven interface for the construction of a block diagram
representation of a process.
A block diagram is simply a graphical representation of a
process (which is composed of an input, the system, and an
output).
About SIMULINK
SIMULINK uses a graphical user interface (GUI) for solving
process simulations.
Instead of writing MATLAB code, we simply connect the
necessary ``icons'' together to construct the block diagram.
The ``icons'' represent possible inputs to the system, parts of the
systems, or outputs of the system.
SIMULINK allows the user to easily simulate systems of linear and
nonlinear ordinary differential equations.
Dynamic simulation packages (such as MATLAB, SIMULINK,
etc.) are being used more and more frequently in the chemical
process industries for process simulation and control system design.
Modeling in SIMULINK
•Linear Systems
•Nonlinear Systems
Modeled in
•Continuous time
•Sampled time (single rate or Multi-rate)
•Hybrid of the two.
Identify the System
Input signals
Output Signals
Intermediate Signals
Parameters
Continuous States
Discrete states
GETTING STARTED IN SIMULINK
To start Simulink, on the
command prompt, type
>>simulink
or
Click here
SIMULINK WINDOW
SOURCES
Sources library contains the
sources of data signals to be
used in the dynamic system
simulation.
E.g. Constant signal, signal
generator, sinusoidal waves,
step input, repeating
sequences like pulse trains
and ramps etc.
SINKS
Sinks library contains blocks where
the signal terminates. You may
store data in a file, display it. Use
the terminator block to terminate
unused signals. STOP block is
used to stop the simulation if the
input to the block is non-zero.
CONTINUOUS AND DISCRETE
Analyze your dynamic
system as continuous or
discrete. Simulink lets
you represent your
system using transfer
functions, integration
blocks, delay blocks etc.
BLOCK DIAGRAM CONSTRUCTION
Basically, one has to specify the model of the system (state space,
discrete, transfer functions, nonlinear ODE's, etc), the input
(source) to the system, and where the output (sink) of the
simulation of the system will go.
Open up the Sources, Sinks, and Linear windows by clicking on
the appropriate icons. Note the different types of sources (step
function, sinusoidal, white noise, etc.), sinks (scope, file,
workspace), and linear systems (transfer function, state space
model, etc.).
The next step is to connect these icons together by drawing lines
connecting the icons using the left-most mouse button (hold the
button down and drag the mouse to draw a line).
SIMPLE EXAMPLE
NONLINEARITIES
In simulation, systems with non-linearities
such as saturation, signum function,
limited slew rates etc. are analyzed by
numerical differentiation.
You may use a saturation block to indicate
a limitation on a voltage signal to a motor.
Manual switches can be used for
simulations with different cases. Switches
are logically equivalent to If-then
statements.
Slew rates using the rate limiter control the
rate of change of a physical parameter such
as the speed of a DC motor etc.
SIMPLE EXAMPLE
E.g. Consider a Sine wave of amplitude 1 (signal varies between
+1 and -1). A saturation block is used to limit the output to an
amplitude of 0.5 and the saturated and original signals are
compared.
SOLVERS
A solver determines the next time step your simulation will take
to meet the accuracy tolerances you specify. Simulink has
Variable step solver
Fixed step solver.
Variable step solver; the time step added to the current time can
vary depending on the dynamics of the system. If your model
contains discontinuities or rapidly changing states use this
solver.
Eg: ODE45, ODE23, ODE11s (stiff solver)
Fixed Step Solver: Step size remains constant. They do not
control integration errors or detect discontinuities. The are
faster.
Eg. ODE1